AU2018227888B2

AU2018227888B2 - Method for producing lithium hydroxide from lithium-containing ore by means of chlorination and chloroalkali process

Info

Publication number: AU2018227888B2
Application number: AU2018227888A
Authority: AU
Inventors: Mostafa BIGLARI
Original assignee: SMS Group GmbH
Current assignee: SMS Group GmbH
Priority date: 2017-02-28
Filing date: 2018-02-02
Publication date: 2021-04-08
Anticipated expiration: 2038-02-02
Also published as: WO2018158035A1; CA3054747C; PT3589762T; PL3589762T3; DE102017221268A1; EP3589762A1; AU2018227888A1; CA3054747A1; EP3589762B1; CN110494574A

Abstract

The invention relates to a method for producing lithium hydroxide (4), in particular high-purity lithium hydroxide, for use in batteries and/or accumulators, from lithium-containing ore and/or mineral, and/or lithium-containing earths (1) by means of a chloroalkali process, wherein a solution is to be provided for increasing the extraction rate of high-purity lithium hydroxide when using a chloroalkali process. This aim is achieved in that in a chlorination step (A) a lithium chloride solution (2) is produced, wherein initially, the lithium-containing ores and/or minerals and/or earths (1) are chlorinated using chlorine gas (5), and subsequently, are leached out, in particular with the use of water. In a subsequent purification step (B), a high-purity lithium chloride solution (3) is generated, wherein the lithium chloride solution (2) is purified, in particular by removing cations, such as sodium, potassium, calcium, magnesium, and/or iron, from the lithium chloride solution (2). In a subsequent electrolysis step (C), lithium hydroxide (4), in particular high-purity lithium hydroxide, is then produced, wherein the high-purity lithium chloride solution (3) is subjected to a membrane electrolysis generating chlorine gas (5) and hydrogen as by-products.

Description

Method for producing lithium hydroxide from lithium-containing ore by means of chlorination and chloroalkali process

The invention is directed to a method for producing lithium hydroxide from lithium containing ore and/or mineral and/or from lithium-containing earths, in particular high purity lithium hydroxide for use in batteries and/or rechargeable batteries. For several years now, a global increase in the demand for the light metal lithium has been observed. Lithium, for example in the form of lithium hydroxide and lithium carbonate, is primarily used for the electrochemical properties thereof in battery applications, in particular for rechargeable batteries and/or storage batteries, known as lithium-ion batteries. These are used, in particular, in portable electrical devices such as cellular telephones, laptops or similar applications. The lithium-ion battery is also increasingly gaining in importance in the automotive industry in electric and hybrid vehicles as an alternative or in addition to the internal combustion engine. As a result, it is to be expected that demand for lithium hydroxide and high-purity lithium carbonate will continue to increase in the future.

At present, lithium is predominantly extracted from brines or salt water obtained from salt lakes, for example, using absorption, evaporation, precipitation and/or ion exchange processes. These sources, however, will not be sufficient to cover the need for lithium arising in the future. The article by MESHRAM et al., Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation, in: Hydrometallurgy 150 (October 2014) 192-208 discloses different natural sources of lithium and methods for the extraction thereof. According to the article, extracting lithium from ores and minerals such as pegmatite, spodumene and petalite or clays, such as hectorite, is more complex than the extraction from brines or salt water, but also possible using a variety of methods, such as the sulfate process or alkali digestion. Typically, lithium hydroxide is extracted from lithium-containing ores by adding sulfate salts or sulfuric acid, followed by several purification steps, and by producing lithium carbonate as an intermediate. The lithium-containing ores are first roasted or calcined, resulting in the

1 11659595_1(GHMatters) P111897.AU leachable lithium mineral B-spodumene. The B-spodumene is subsequently leached with sulfuric acid to yield an aqueous lithium sulfate solution. Magnesium, iron and calcium are incrementally removed from the solution by adding lime milk and sodium carbonate. By adding more sodium carbonate to the solution, it is possible to precipitate as much as 98% of the lithium present in the solution in the form of lithium carbonate. In another process step, the resultant lithium carbonate is converted to lithium hydroxide. The direct precipitation of lithium hydroxide from the solution using sodium hydroxide is also prior art.

More recent developments are aimed at the direct production of lithium hydroxide by means of the chloroalkali process without first producing lithium carbonate. A method for producing lithium hydroxide from a lithium chloride solution is known from US 2011/0044882, for example. A lithium-containing solution, which can be obtained from brines or ores, is first concentrated and then subjected to various purification steps, such as adjustment of the pH to precipitate divalent or trivalent ions or ion exchange to reduce the overall concentration of calcium and magnesium. The concentrated and purified lithium chloride solution is subjected to electrolysis, wherein a semipermeable membrane selectively passes lithium ions, whereby a lithium hydroxide solution is obtained, with chlorine and hydrogen as by-products. Chlorine gas is produced at the anode of the electrolysis device, and lithium hydroxide and hydrogen are produced at the cathode. The total content of calcium and magnesium in the high-purity lithium hydroxide solution is less than 150 ppb (number of parts per billion).

To produce the lithium chloride solution, it is proposed in AU 2013 20 18 33 B2 to extract the lithium present in the ore by leaching B-spodumene with hydrochloric acid. In a subsequent purification step, the resultant solution is purified and concentrated so as to then pass it to the electrolysis step. According to the article NOGUEIRA et al., Comparison of Processes for Lithium Recovery from Lepidolite by H2SO4Digestion or HCI Leaching, Proc. Inter. Con. Min. Mater. and Metal. Eng. 2014), the lithium extraction rate for the resultant lithium chloride solution is less than 84% with this production approach. Moreover, an alternative method for producing a lithium chloride solution is

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11659595_1 (GHMattes) P111897.AU known from the article YAN et al., Extraction of lithium from lepidolite using chlorination roasting - water leaching process, Trans. Nonferrous Met. Soc. China 22 (2012), 1753. According to the described method, lepidolite is first comminuted and, for the chlorination stage, is mixed with a mixture of sodium chloride and calcium chloride. The resulting lithium chloride solution contains 92% of the lithium fraction of the ore.

A method for extracting lithium chloride from a gas phase resulting during the chlorination reaction is known from US 2005/220691 Al. For this purpose, the volatile components present in the gas phase and combustion gases, such as CO and C02, are taken from the reactor by vacuum and fed to a condenser. As the vacuum progresses, the volatilized lithium chloride also enters the condenser. The condenser can be operated at room temperature, so that the gaseous reaction products typically condense to solids.

From other sources, processes for producing lithium chloride solutions having higher lithium recovery rates are known. For example, the article BARBOSA et al., Kinetic study on the chlorination ofR-spodumene for lithium extraction with C12 gas, Miner Eng.56 (2014) 29-34 shows a possible process approach for extracting lithium from lithium-containing ore. The naturally occurring alpha crystalline form of spodumene present in the ore is first calcined to convert the spodumene into the beta crystalline form. The R-spodumene is subsequently chlorinated with pure chlorine gas, the resulting lithium chloride solution containing 100% of the lithium present in the spodumene.

The disadvantages of the known prior art are the high costs and the, at times, low yield of lithium or lithium hydroxide from the lithium-containing ores and/or minerals and/or earths. In particular, high amounts of sodium carbonate are consumed when precipitating lithium carbonate from a lithium sulfate solution. However, sodium carbonate is subject to high price fluctuations in the market, whereby a method for producing lithium hydroxide by way of lithium carbonate as an intermediate has an increased risk in terms of cost. In AU 2013 20 18 33 B2, the production of lithium

3 11659595_1 (GHMattes) P111897.AU carbonate as an intermediate is bypassed by extracting lithium hydroxide from a lithium chloride solution by means of the chloroalkali process. The lithium chloride solution is obtained by leaching B-spodumene with hydrochloric acid. The yield of lithium is also comparatively low with this procedure due to the leaching with hydrochloric acid. Higher lithium recovery rates could be achieved through longer process times and by increasing the process temperature; however, this adversely affects the cost effectiveness of the approach.

It is therefore the object of the invention to create a solution that allows the extraction rate of high-purity lithium hydroxide with the use of a chloroalkali process to be increased in a method for producing lithium hydroxide from lithium-containing ore and/or mineral and/or lithium-containing earths.

This object is achieved according to the invention by a method according to claim 1. In the method according to the invention for producing lithium hydroxide from lithium containing ore and/or mineral and/or lithium-containing earths, and in particular for producing high-purity lithium hydroxide for use in batteries and/or rechargeable batteries, lithium chloride is produced in a chlorination step, wherein the lithium containing ores and/or minerals and/or earths are first chlorinated using chlorine gas, and in particular pure and/or elemental chlorine gas. Depending on the design of the chlorination process, the lithium chloride, according to an advantageous embodiment, is present in the roasted material resulting from the chlorination step or, according to another advantageous embodiment, is moved out of the reactor chamber with a gas phase volatilizing during the chlorination step and is extracted separately at a lower temperature. The lithium chloride can be evaporated and/or the lithium present in the spodumene can be transferred into the gas phase by chlorination, for example, at low pressure. In a subsequent purification step, a high-purity lithium chloride solution is then generated, wherein the previously produced lithium chloride solution still containing impurities is purified, in particular by removing cations such as sodium and/or potassium and/or calcium and/or magnesium and/or iron from the lithium chloride solution. In a subsequent, in particular final, electrolysis step, lithium hydroxide is then produced,

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11659595_1 (GHMattes) P111897.AU wherein the high-purity lithium chloride solution is subjected to a membrane electrolysis step, creating chlorine gas and hydrogen as by-products.

According to the invention, a direct production of lithium hydroxide from an ore and/or a mineral and/or an earth is thus proposed, without producing lithium carbonate as an intermediate, with a drastically reduced use of chemicals, and in particular with a drastically reduced use or even without the use of sodium carbonate and/or without the use of acids, in particular hydrochloric acid or sulfuric acid, compared to the known prior art. For this purpose, the lithium-containing ore and/or mineral and/or the lithium containing earth is first chlorinated in a chlorination step, using chlorine gas, and preferably using pure and/or elemental chlorine gas (C12). Compared to other roasting or extraction methods, no excess chemicals arise during the chlorination with chlorine gas. This is attributable to the fact that the elemental chlorine used for chlorination is present in gaseous form and remains separate from the roasted material when no reaction takes place. The chlorine gas has already volatilized before the subsequent leaching step. Chlorination with, in particular pure and/or elemental, chlorine gas instead of roasting with hydrochloric acid or chlorides improves the recovery rate and/or the yield of the lithium present in the produced lithium chloride solution, relative to the lithium content of the ore and/or of the mineral and/or of the earth. By means of the chlorination with pure, elemental chlorine gas (C12), it is possible to almost completely or to completely extract lithium from the lithium-containing ore and/or mineral and/or the earth. Water is preferably used for leaching the lithium chloride, also with respect to the later electrolysis step.

In a purification step, a high-purity lithium chloride solution is obtained from the produced lithium chloride solution still containing impurities. This means, in particular, that the content of lithium present in the solution is increased compared to other ions. In particular, cations such as sodium and/or potassium and/or calcium and/or magnesium and/or iron are removed from the lithium chloride solution. This is likewise advantageous with respect to the electrolysis step to be carried out thereafter, in which

5 11659595_1 (GHMattes) P111897.AU not only the lithium to be extracted, but also undesirable cations precipitate on the cathode.

The invention thus combines the advantages of two methods known from the prior art for producing lithium hydroxide, by applying individual method steps of a production method utilizing the extraction of lithium carbonate as an intermediate to a chloroalkali production approach and/or replacing individual steps of the chloroalkali production approach and/or adapting these thereto.

In an advantageous embodiment, the method according to the invention is characterized in that the chlorine gas generated in the electrolysis step is selectively used, at least partially, in the chlorination step to chlorinate the lithium-containing ores and/or minerals and/or earths. From a stoichiometric point of view, the amount of the chlorine gas generated in the electrolysis step preferably corresponds to the amount of the chlorine gas added in the chlorination step for chlorination, so that the chlorine gas generated by means of electrolysis is completely recirculated and is circulated in such a way that it is not necessary to add further and/or additional chlorine gas, or only to a very small degree. A particular effect of the advantageous embodiment of the invention is thus the combination of the chlorine gas-consuming chlorination of the chlorination step with the chlorine gas-producing chloroalkali electrolysis of the electrolysis step. The chlorine gas used in a preceding method step, this being the chlorination step, is preferably completely recovered again in a subsequent method step, this being the electrolysis step, and preferably is completely recirculated for use in the preceding method step, this being the chlorination step.

According to an advantageous embodiment of the invention, the lithium chloride containing roasted material obtained from the chlorination step is leached, subsequent to the chlorination step, with water to produce a lithium chloride solution.

An advantageous embodiment of the invention provides that lithium chloride-containing gaseous components that volatilize during the chlorination step are condensed

6 11659595_1 (GHMattes) P111897.AU subsequent to the chlorination step, and in particular prior to leaching, to produce a lithium chloride solution. The gaseous phase created during chlorination is first transported out of the reactor and subsequently condensed to extract the lithium chloride contained therein, in particular at room temperature. Subsequent to the condensing, the condensate is leached with water to produce the solution. Depending on the design of the chlorination, consequently two alternative method steps are provided to produce the lithium chloride solution, namely leaching of the roasted material by means of water on the one hand, and condensing the volatile components, which requires less thermal energy, followed by leaching.

The invention is also characterized in that the chlorine gas generated in the electrolysis step is selectively recombined, at least partially, with the hydrogen likewise generated in the electrolysis step, in particular by means of an HCI generator, to give hydrochloric acid. The hydrochloric acid generated thereby can be withdrawn as a by-product of the lithium hydroxide production process. Overall, the chlorine gas obtained in the electrolysis can thus be selectively recirculated, completely or partially, to the chlorination process and/or be recombined, completely or partially, with the hydrogen likewise generated in the electrolysis step to generate hydrochloric acid. To the extent that the hydrogen cannot be utilized to produce hydrochloric acid, it can be further used in the known manner for other processes and/or be stored and/or stocked, for example, for later sale or for later use.

Compared to the sulfate method, in which the lithium-containing ore and/or mineral and/or the lithium-containing earth, in particular lepidolite, is roasted, and the resultant B-spodumene is digested by means of sulfuric acid, the chlorination with chlorine gas, and in particular with pure and/or elemental chlorine gas, has a higher, in particular 100%, yield of lithium. Leaching of the solution is preferably carried out with water, so that lithium hydroxide and selectively hydrogen (H2) and chlorine gas (C12) and/or hydrochloric acid (HCI) can subsequently be obtained from the produced lithium chloride solution by means of the chloroalkali process.

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11659595_1 (GHMattes) P111897.AU

Advantageously, cations that are present in the lithium chloride solution prior to the electrolysis step and impair the electrolysis, in particular iron and/or calcium and/or magnesium, should be reduced to very low concentrations. In an advantageous refinement, the invention provides that the lithium chloride solution is purified in the purification step by setting the pH of the lithium chloride solution, in particular to a pH value of greater than 8, wherein the pH is preferably increased by adding a lye, comprising, in particular, hydroxides and/or carbonates, and/or an alkaline solution. By increasing the pH, in particular to a pH value of greater than 8, it is possible to precipitate, and subsequently eliminate, undesirable ions such as aluminum, iron, magnesium and manganese in the form of corresponding hydroxides from the lithium chloride solution. The oxidization of iron present in the lithium chloride solution, for example, offers another option, wherein chemical substances suitable for oxidizing iron are added to the lithium chloride solution. Advantageously, calcium can be removed from the lithium chloride solution in the purification step by adding alkali carbonate, and in particular lithium carbonate and/or sodium carbonate. Optionally, a portion of the chlorine gas added to the chlorination of the lithium-containing ore and/or mineral and/or of the lithium-containing earth can also be converted to calcium chloride, wherein calcium impurities present in the ore and/or in the mineral and/or in the earth react with the chlorine gas to give calcium chloride. In a further embodiment, the invention thus provides that the lithium chloride solution is purified in the purification step by adding alkali carbonate, and in particular lithium carbonate and/or sodium carbonate, wherein, in particular, calcium is removed from the lithium chloride solution. The resultant calcium carbonate can be eliminated from the lithium chloride solution, whereas the added lithium is recovered in the electrolysis step.

Furthermore, the produced lithium chloride solution can also be subjected to an ion exchange process, and in particular to a cation exchange process, to further reduce the cations present in the lithium chloride solution. The invention thus also provides that the lithium chloride solution, in the purification step, is subjected to an ion exchange process, and in particular to a cation exchange process, to further reduce the cations present in the lithium chloride solution.

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An optional purification of the lithium chloride solution in the purification step by fractional crystallization is likewise advantageous, wherein lithium and/or sodium and/or potassium are separated from one another, and the sodium and/or potassium precipitate as sodium chloride or potassium chloride, which is provided by the invention in a refinement.

The lithium chloride solution can also be further purified by employing solvent extraction. The lithium to be obtained is separated from other alkali salts, and in particular sodium chloride, in the process. Finally, the invention is thus also characterized in that the lithium chloride solution is purified in the purification step by solvent extraction, wherein lithium is separated from other alkali salts, and in particular sodium chloride.

Further options for purifying the lithium chloride solution known from the prior art can be employed as an alternative or option to the above-described purification options during the purification step of the production method according to the invention.

The invention is described in more detail hereafter by way of example based on a drawing. The

figure shows a process flow chart of an exemplary method according to the invention for producing lithium hydroxide from lithium-containing ore and/or mineral and/or a lithium-containing earth.

In the figure, a process flow chart of an exemplary method according to the invention for producing lithium hydroxide from lithium-containing ore and/or mineral and/or a lithium containing earth (1) is shown. According to the exemplary embodiment, the lithium containing mineral or earth (1) spodumene (LiAI[Si2O6]) is used as the starting product for producing lithium hydroxide (4), which is obtained as the end product of the production method according to the invention for further use in battery applications, and

9 11659595_1 (GHMattes) P111897.AU in particular for rechargeable lithium-ion batteries. In particular, high-purity lithium hydroxide can be obtained by means of the production method according to the invention, having an overall content of undesirable foreign cations, such as calcium and magnesium, of less than 150 ppb (number of parts per billion). Spodumene occurs in lithium-containing ores (1), and in particular in lepidolite. The treatment of the lithium containing ore and/or mineral (1) for further processing according to the invention can usually take place by crushing and grinding of the pieces of rock. The overall reaction of the exemplary embodiment according to the invention for producing lithium hydroxide (4) from the lithium-containing mineral (1) spodumene is shown hereafter:

4 LiAISi2O6+ 4 H20 -> 4 LiOH + 2 A2Si4O11 + 02 + 2H2

In a chlorination step (A), the lithium-containing mineral (1) spodumene is first roasted for 2 hours at a temperature of 11000C, adding chlorine gas (C12) (5). The reaction of spodumene with chlorine gas (5) is shown hereafter:

LiAISi2O6 + 1/2CI2(g) -> 1/402(g) + LiCI + 1/2Al2Si4011

Excess chlorine gas (5) and/or chlorine gas not converted to lithium chloride (LiCI) volatilizes before subsequently the leaching with water is carried out at a temperature of °C. As an alternative, the chlorination can be carried out at low pressure, whereby the lithium chloride is present in the gaseous phase. The gaseous phase is condensed prior to the leaching with water at room temperature. Compared to leaching with acid, such as hydrochloric acid or sulfuric acid, the use of water is less hazardous, more cost effective and advantageous for a chloroalkali process following later.

The yield, that is, the extracted fraction of lithium in relation to the total amount of lithium present in the starting product, is 100% in the exemplary embodiment. The fraction of excess chemicals in the lithium chloride solution (2) still containing impurities is 0% due to complete reaction of the lithium present in the spodumene and the volatility of the possibly excess chlorine gas (5). Optionally, a portion of the chlorine gas (5) added to

10 11659595_1 (GHMattes) P111897.AU the chlorination of the lithium-containing ore and/or mineral and/or of the lithium containing earth (1) can also be converted to calcium chloride, wherein calcium impurities present therein react with the chlorine gas (5) to give calcium chloride. A precipitation reaction for calcium chloride by the addition of sodium carbonate can be carried out in the subsequent purification step (B) and is as follows:

CaC12 + Na2CO3 -> CaCO3 + 2 NaCl

In a purification step (B), the lithium chloride solution (2) is treated or purified further to obtain a high-purity lithium chloride solution (3). A high-purity lithium chloride solution (3) is characterized, in particular, by a very low content of undesirable foreign cations such as sodium, potassium, magnesium, calcium and iron. In particular, the total content of magnesium and calcium, based on the total ion amount, is less than 150 ppb (number of parts per billion). As described above, the removal of foreign cations and other purification can be carried out by setting the pH to a pH value of > 8 of the lithium chloride solution (2), by adding chemical substances for oxidizing iron, by means of separation by fractional crystallization, separation by solvent extraction and/or by ion exchange.

The high-purity lithium chloride solution (3) obtained by means of the purification step (B) is subjected to an electrolysis step (C) so as to extract lithium hydroxide (4). A chloroalkali process is carried out in the electrolysis step (C) using a membrane electrolysis device comprising a semipermeable membrane. An anode and a cathode of the electrolysis device are separated from one another by the semipermeable membrane. The ions present in the high-purity lithium chloride solution (3) are separated from one another by the application of a voltage, wherein lithium hydroxide (4) is obtained as the primary product and hydrogen is obtained as a by-product of the electrolysis at the cathode, and chlorine gas (5) is obtained as a by-product at the anode. Since undesirable foreign cations were already removed from the lithium chloride solution (2) in the purification step (B) so as to obtain a high-purity lithium

11 11659595_1(GHMatters) P111897.AU chloride solution (3), the lithium hydroxide (4) accumulating at the cathode can likewise be removed in high-purity form, that is, substantially free from undesirable cations.

The obtained by-products, these being hydrogen and chlorine gas (5), can be recombined to hydrochloric acid by means of an HCI generator (6). By producing an easily marketable by-product, such as hydrochloric acid, the economic efficiency of the method according to the invention can be further increased. As an alternative, the chlorine gas (5) obtained in the electrolysis step (C) can be partially, or preferably completely, recirculated so as to be utilized in the chlorination step (A) for the chlorination of the lithium-containing minerals and/or ore and/or earths (1). In this way, the need for chlorine gas (5) required for chlorination can be drastically lowered or reduced to zero by circulating the chlorine gas (5). The hydrogen obtained at the cathode can then be stored and/or stocked for later use or be supplied to another process for direct further use.

The extracted, in particular high-purity, lithium hydroxide is suitable for use in battery applications, and in particular for use in rechargeable lithium-ion batteries, or for further processing, for example to lithium carbonate, and in particular high-purity lithium carbonate.

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List of Reference Numerals

1 lithium-containing ores and/or minerals and/or earths 2 lithium chloride solution 3 high-purity lithium chloride solution 4 lithium hydroxide chlorine gas 6 HCI generator A chlorination step B purification step C electrolysis step

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Claims

1. A method for producing lithium hydroxide (4), in particular high-purity lithium hydroxide for use in batteries and/or rechargeable batteries, from lithium containing ore and/or mineral and/or lithium-containing earths (1) by means of a chloroalkali process, comprising: - producing, in a chlorination step (A), a lithium chloride solution (2), wherein the lithium-containing ores and/or minerals and/or earths (1) are first chlorinated using chlorine gas (5); - then generating, in a subsequent purification step (B), a high-purity lithium chloride solution (3), wherein the lithium chloride solution (2) is purified, in particular by removing cations such as sodium, potassium, calcium, magnesium and/or iron from the lithium chloride solution (2); and - then producing, in a subsequent electrolysis step (C), lithium hydroxide (4), and in particular high-purity lithium hydroxide, wherein the high-purity lithium chloride solution (3) is subjected to a membrane electrolysis step generating chlorine gas (5) and hydrogen as by-products.

2. The method according to claim 1, characterized in that the chlorine gas (5) generated in the electrolysis step (C) is selectively used, at least partially, in the chlorination step (A) for the chlorination of the lithium-containing ores and/or minerals and/or earths (1).

3. The method according to claim 1 or 2, characterized in that, subsequent to the chlorination step (A), the lithium chloride-containing roasted material obtained from the chlorination step (A) is leached with water to produce a lithium chloride solution (2).

4. The method according to claim 1 or 2, characterized in that lithium chloride containing gaseous components that volatilize during the chlorination step (A)

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11659595_1 (GHMattes) P111897.AU are condensed subsequent to the chlorination step (A) to produce a lithium chloride solution (2).

5. The method according to any one of the preceding claims, characterized in that the chlorine gas (5) generated in the electrolysis step (C) is selectively recombined, at least partially, with the hydrogen generated in the electrolysis step (C), in particular by means of an HCI generator (6), to give hydrochloric acid.

6. The method according to any one of the preceding claims, characterized in that the lithium chloride solution (2) is purified in the purification step (B) by setting the pH, in particular to a pH value of greater than 8, the pH preferably being increased by adding a lye comprising hydroxides and/or carbonates, and/or an alkaline solution.

7. The method according to any one of the preceding claims, characterized in that iron present in the lithium chloride solution (2) is oxidized in the purification step (B), chemical substances suitable for oxidizing iron being added to the lithium chloride solution (2).

8. The method according to any one of the preceding claims, characterized in that the lithium chloride solution (2) is purified in the purification step (B) by adding alkali carbonate, and in particular lithium carbonate and/or sodium carbonate, in particular calcium being removed from the lithium chloride solution (2).

9. The method according to any one of the preceding claims, characterized in that the lithium chloride solution (2), in the purification step (B), is subjected to an ion exchange process, and in particular to a cation exchange process, to further reduce the cations present in the lithium chloride solution (2).

10. The method according to any one of the preceding claims, characterized in that the lithium chloride solution (2) is purified in the purification step by fractional

15 11659595_1 (GHMattes) P111897.AU crystallization, lithium and sodium and/or potassium being separated from one another, and the sodium and/or potassium precipitating as sodium chloride or potassium chloride.

11. The method according to any one of the preceding claims, characterized in that the lithium chloride solution (2) is purified in the purification step (B) by solvent extraction, lithium being separated from other alkali salts, and in particular sodium chloride.

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